Well... To get technical, the ability to call the Guardian to a certain place counts as a very limited kind of control. But yeah, Macha is the one who has complete control over the Guardian's actions. Also, you said that Tsukasa could only hope that his Guardian would appear. Did it ever ignore his call? I don't remember it doing that, but my memory of SIGN is far from perfect.
It never ignored Tsukasa when he called it, but it usually would do whatever it felt like, and didn't listen to Tsukasa's orders... such as when it tried to attack Bear and Mimiru, or when it killed that party of girls.
And there are the times it appears without being called, such as in episode 14.
"Hark he of Fair eyes, I am CRtwenty of the Azure Keyboard!"
Actually, the Dawn Wanderer is blueish purple, only the regular Guardian is gold. Then there's also the Temptress Lover, which seems to 'evolve' from the Dawn Wanderer.
You're only young once, but you're NEVER too old to be immature.
You're right, my mistake. It's been a while since I completed that dungeon. It's the Temptress Lover that has some gold on it. The Dawn Wanderer is a shade of purple, but it's not the same color as the blue Guardians in Episode 25 of SIGN.